<template>
    <div>
      <router-link
        to="/"
        tag="div"
        class="header-abs"
        v-show="showAbs"
      ><span class="iconfont header-abs-back">&#xe624;</span></router-link>
      <div class="header-fixed"
           v-show="!showAbs"
           :style="opacityStyle"
      >
        <router-link to="/">
          <div class="iconfont header-fixed-back">&#xe624;</div>
        </router-link>
        景点详情
      </div>
    </div>
</template>

<script>
export default{
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  activated () {
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll', this.handleScroll)
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      console.log(top)
      if (top > 50) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {
          opacity: opacity}
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  }
}
</script>

<style type="text/css" lang="scss" scoped>
.header-abs{
  position: absolute;
  left: .2rem;
  top: .2rem;
  width: .8rem;
  height: .8rem;
  line-height: .8rem;
  text-align: center;
  border-radius: .4rem;
  background: rgba(0,0,0,0.8);
  .header-abs-back{
    color: #fff;
    font-size: .4rem;
  }
}
.header-fixed{
  position: fixed;
  width: 100%;
  top:0;
  height:$headerHeight;
  line-height: $headerHeight;
  text-align: center;
  color: #fff;
  background: $bgColor;
  font-size: .32rem;
  z-index: 9;
  .header-fixed-back{
    position: absolute;
    width: .64rem;
    top:0;
    left:0;
    text-align: center;
    font-size: .4rem;
    color: #fff;
  }
}

</style>
